Condition responsive switching device



Nov. 15, 1949 v. WEBER ETAL 2,488,459

CONDITION RESPbNSIVE SWITCHING DEVICE Filed March 14, 1947 vzc roe, weak-2,4 v wzu. mm s. KUNZLER.

Federated in,

GO NDITION RESPONSIVE SWHTQHHilG DEVICE Victor Weber and William S. Kunzier, Greens burg, Pa, assignors to Robertshaw-Fulton 63cm trols Company, a corporation of Delaware Application March 14, 1947, Serial No. 2134,61?

8 Claims.

This invention relates to electric switching devices and, more particularly, to automatic de= vices operable by condition responsive means such as temperature or pressure conditions.

of the invention is to control a circuit at a predetermined temperature or pressure within the range of operation of the device.

Another object of the invention is to render the switch construction of a compact and simple nature with a minimum of moving parts.

Another object of the invention is to ensure positive operation of the switch contacts at the desired temperature or pressure setting.

Another object of the invention is to utilize a substantially rigid switch arm construction having a yieldable mounting which both positions the parts and provides contact pressure.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. 1 is a longitudinal section of the switching device;

Fig. 2 is a cross section taken on the line IIII of Fig. 1;

Fig. 3 is a perspective view of two of the parts in separated relation.

Referring more particularly to the drawing, a

casing ill having a front cover i2 is provided for housing the switching mechanism. A first switch arm it which is substantially rigid and stationary with respect to the casing it is mounted therein on an insulating block it secured at one end of the casing it]. The switch arm 94 carries first contact means it which, as indicated in broken lines in Fig. 2, may be a contact pair. Cooperable with the first contact means it is a second contact means 213 in the form of a contact bar serving to bridge the contact means l8 when in engagement therewith. The second contact means 20 is carried on one end of a second switch arm 22 which is also substantially rigid and corn prises more specifically an insulating portion 24 to which the contact means 20 is secured and a blade portion 25 to which the insulating portion it is secured.

In order that the contact means it and 20 may be disengaged when desired the second switch arm 22 is movable with respect to the stationary switch arm i i. The blade portion 26 is formed oil of sheet material, such as metal, and has a base 28 formed at an angle thereto and provided with a pair of spaced abutments 30 on opposite ends thereof. Intermediate the abutments so the base 28 carries a projection provided with a notch M of sufficient depth to provide an end surface substantially coplanar with the end surfaces of the abutments so. The blade portion 26 is further provided with a window 36 having a flap 38 depending at an oblique angle from the upper wall thereof toward the base 28. The flap 38 has an aperture it formed therein with the wall thereof swaged or otherwise turned inwardly to provide an annular seat portion 42 facing toward the window it.

A support member M which may also be of sheet material, such as metal. is positioned in the casing iii adjacent the base 28 of the movable switch arm 22. The support 44 is of channel iorm to accommodate the base 28 of the movable switch arm 22 therewithin. The two opposite ends of the channel-shaped support it are turned outwardly to provide oppositely disposed lugs 46 by which the support it is secured to the casing ill. An aperture 4% is formed in thesupport 4t intermediate the lugs it to receive the notched end as of the projection 32 when the movable switch arm 22 is positioned on the support 44.

As will be apparent from Figs. 1 and 2 of the drawing, when the movable switch arm 22 is positioned on the support M, the end surfaces of the abutments 3t and the end surface of the notch 345 all engage the underside of the support 44 due to the stated coplanar arrangement. It will further be apparent that the arrangement provides means for pivoting the movable switch arm 22 on the support M for rotation relative to the stationary switch arm it. While the engagement of the notch 34 with the aperture 48 provides a pivot for the movable switch arm 22,

it is also evident that the abutments 30 are cooperating elements to preclude any transverse tilting of the movable switch arm 22 during the pivoting movement. The support 44 is further provided with a tongue portion 5!] which projects toward the blade 26 and has a flap 5? thereon projecting at an oblique angle through the window at and extending substantially parallel with the flap 38. The nap 52 is apertured similar 3 to the flap 3a and is thus formed with an annular seat 54 opposite the annular seat 42.

Yieldable means comprising a coil spring 56 is provided for biasing the movable switch arm 22 to engage the contact means 20 with the contact means H3. The coil spring 56 is positioned at one end on the annular seat 42 and at the opposite end upon the annular seat 54. Such arrangement establishes an angular relation of the coil-spring 56 to the movable switch arm 24 as shown in Fig. 1 of the drawing and the spring bias will normally maintain the movable switch arm 22 in substantially parallel relation with the stationary switch arm l4 with the contacts l8 and 20 engaged.

Condition responsive means are provided for exerting a force on the movable switch arm 22 for overcoming the bias of the coil spring 56 causing rotation of the movable switch arm 22 to move the contact means 20 in an arcuate path away from the contact means [8. To this end, an actuating element 58 is operatively engageable with the movable switch arm 22 intermediate the contact means 20 thereon and the pivot therefor provided by the notch 34 and aperture 48. The actuating element 58 is connected by means of a capillary tube 60 to a thermal device or a source of variable pressure depending upon whether it is desired that the actuating element 58 respond to changes in temperature or changes in pressure. The capillary tube 60 projects exteriorly of the casing Ill and may be anchored thereto without preventing axial movement of the actuating element 58 due to the inherent resiliency of the capillary tube 80. A stud 62 projects from the actuating element 58 and has a reduced portion 64 slidably supported within an axially apertured threaded stem 66 which projects through the front cover i2. The re duced portion 64 defines a shoulder on the stud 62 which is engageable by the terminal end of th threaded stem 56. The stem 66 is rotatable in a nut 68 which is secured against rotation in the front cover l2.

In order to limit rotation of the stem 66 to less than one complete revolution the nut 68 is provided with a collar IIJ adjustably secured thereto and having a finger 12 projecting therefrom. The finger I2 is adapted to engage a detent 14 projecting laterally from the stem 66 beyond the nut 68. The arrangement provides adjustable stop means operatively associated with the casing l and the threaded stem 66 for limiting relative rotation therebetween.

A handle 16 is secured to the threaded stem 66 and carries the usual indicia (not shown) for the various temperatures and pressures at which the switching device is designed to operate. The handle is rotatable with the threaded stem 66 to register the selected temperature or pressure marking with the usual index line marked on the front cover l2 for this purpose. It will be apparent that operation of the handle 16 will serve to rotate the stem 66 and, due to its threaded engagement with the nut 68, the stem 66 will move axially to position the actuating means 58 relative to the movable switch arm 22.

When the parts are positioned as shown in Figs. 1 and 2 of the drawing it will be apparent that expansion of the actuatin element 58 in response to an increase in temperature or pressure will serve to exert a force on the movable switch arm 22 for overcoming the bias of the coil spring 55. The movable switch arm 22 is thus rotated on the pivot 34, 48 to move the contact means in an arcuate path away from the contact means I8 and thus open any circuit connected to the stationary switch arm I4. Due to the arrangement of the actuating element 58 which engages the movable switch arm 22 intermediate the contact means 20 and the pivot 34, 48, a positive break is provided at the contact means 18, 20 upon expansion of the actuating element 58.

Upon contraction of the actuating element 58 due to a decrease in the temperature or pressure to which it responds, then the force exerted thereby upon the movable switch arm 22 is removed and the contact means l8 and 20 are reengaged under bias of the coil spring 56. Should operation of the switching device at a different temperature or pressure be desired, then the handle 16 can be rotated to adjust the threaded stem 66 relative to the actuating element 58 for this purpose.

The adjustable stop means provided by the detent l4 and the finger '12 serves to prevent damage to the switching device such as might occur due to the threaded stem 66 being moved too far in or out by operation of the handle 16. Calibration of the control is readily accomplished by removal of the handle 16 and adjustment of the collar 10 relative to the nut 68 which permits location of the stem E6 in required position relative to the actuating element 58 according to the temperature indicia on the handle 16 when replaced.

While a preferred embodiment of the invention has been shown and described, it is apparent that many other modifications will occur to those skilled in the art. Hence, the invention is not deemed to be limited to the form shown and described or otherwise than as defined within the scope of the claims appended hereto.

We claim:

1. An automatic switching device comprising in combination, a stationary switch arm, a movable switch arm cooperable with said stationary switch arm, a support, means for establishing a bearing relation between said support and said movable switch arm for pivotal movement of the latter relative to said stationary switch arm but being incapable of maintaining said relation, yieldable means operative between said support and said movable switch arm for biasing the latter toward said stationary switch arm, and condition responsive means for rotating said movable switch including an element movable between positions for rotating said movable switch arm against said bias, said yieldable means being effective for exerting its bias intermediate said support and said condition responsive means for maintaining said bearing relation irrespective of the position of said movable element.

2. An automatic switching device comprising in combination, a stationary switch arm, a movable switch arm cooperable with said stationary switch arm and being substantially rigid, a support positioned adjacent one end of said movable switch arm, means for establishing a hearing relation between said support and said movable switch arm for pivotal movement of the latter relative to said stationary switch arm but being incapable of maintaining said relation, yieldable means operative between said support and said movable switch arm for biasing the latter toward said stationary switch arm, and condition responsive means including an element movable between positions for rotating said movable switch arm against said bias, said yieldable means being efiective for exerting its bias intermediate said support and said condition responsive means for maintaining said bearing relation irrespective of the position of said movable element.

3. An automatic switching device comprising in combination, a stationary switch arm having contact means thereon, a movable switch arm having contact means at one end thereof cooperable with the first said contact means, a support positioned adjacent the opposite end of said movable switch arm, means for'establishing a bearing relation between said support and said opposite end of said movable switch arm for pivotal movement of the latter relative to said stationary switch arm but being incapable of maintaining said relation, yieldable means operative between said support and said movable switch arm for biasing the latter toward said stationary switch arm to maintain said contact means closed, and condition responsive means including an element movable between positions for rotating said movable switch arm against said bias for opening said contact means, said yieldable means being effective for exerting its bias intermediate said support and said condition responsive means for maintaining said bearing relation irrespective of the position of said .movable element.

4. An automatic switching device comprising in combination, a stationary switch arm having contact means thereon, a movable switch arm having second contact means at one end thereof cooperable with the first said contact means and being substantially rigid, a support positioned adjacent the opposite end of said movable switch arm, means projecting between said movable switch arm and said support forming a bearing relation therebetween for pivoting said movable switch arm on said support for rotation relative to said stationary switch arm, said projecting means being incapable of maintaining said bearing relation, yieldable means positioned in angular relation to said movable switch arm for biasing the latter toward said stationary switch arm to engage said first and second contact means and being efi'ective on said projecting means for maintaining said. bearing relation, condition responsive means operatively engageable with said movable switch arm intermediate said second con-= tact means and said pivot means for rotating said movable switch arm against said bias and disengaging said first and second contact means at a predetermined condition value while said yieldable means maintains said bearing relation, and means operatively associated with said condition responsive means for adjusting the same to cause said rotation of said movable switch arm at difierent condition values.

5. An automatic switching device comprising a casing, a switch arm supported against relative movement in said casing, a second switch arm positioned on one side of said first switch arm, means carried by said casing for mounting said second switch arm for pivotal movement into and out of operative relation with said first switch arm, yieldable means operative between said mounting means and said second switch arm for biasing the latter into said operative relation, condition responsive means positioned on the opposite side of said first switch arm and having operative engagement with said second switch arm for rotating the same out of said operative relation, means threadedly engaging said casing for supporting said condition responsive means therein, adjustable stop means operatively asso ciated with said casing and said threaded means for limiting relative rotation thereof, and a handle carried by said threaded means for adjusting the same relative to said condition responsive means to cause rotation of said second switch arm at different predetermined condition values.

6. An automatic switching device comprising in combination, a casing, stationary contact means carried by said casing, movable contact means cooperable with said stationary contact means, a switch arm upon which said movable contact means is mounted and having an angularly extending portion thereon, a support carried by said casing and extending adjacent said portion, means operative between said support and said portion for positioning said switch arm for pivotal movement relative to said stationary contact means but being incapable of maintaining said position, yield-able means operable between said support and said switch arm for maintaining pressure between said movable and stationary contact means and concomitantly maintaining said position of said switch arm, and condition responsive means carried by said casing and being effective for overcoming said yieldable means to rotate said switch arm and relieve said pressure while said yieldable means maintains said position of said switch arm.

' 7. An automatic switching device comprising in combination, a casing, stationary contact means carried by said casing, movable contact means cooperable with said stationary contact means, a switch arm member upon which said movable contact means is mounted and having a window opening and an angularly extending portion, a support member carried by said casing having a projection overlying said portion and extending through said window, an abutment on one of said members cooperable with a slot in the other said member for positioning said switch arm member for pivotal movement relative to said stationary contact means, yieldable means extending from said projection through said window in angular relation to said switch arm memher for engagement with one side thereof to maintain pressure between said movable and stationary contact means and concomitantly maintaining said abutment cooperable with said slot, and condition responsive means carried by said casing and operatively engageable with an opposite side of said switch arm intermediate said movable contact means and said yieldable means for overcoming the latter to rotate said switch arm and relieve said pressure while said yieldable means maintains said abutment cooperable with said slot.

8. An automatic switching device comprising in combination, a casing, a pair of stationary contact means carried by said casing, a pair of mov able contact means cooperable with said stationary contact means, a switch arm member upon which said movable contact means is mounted at one end and having a, portion extending from the opposite end substantially normal to the plane of said switch arm, a pair of spaced abutments on said portion, a projection intermediate said abutments having a notch in substantially coplanar relation thereto, a support carried by said casing and overlying said abutments and said projection, said support having a slot therein for receiving said notch and positioning said switch arm for pivotal movement relative to said stationary contact means, yieldable means operative between said support and said switch arm and extending in angular relation thereto for mairn 7 8 taining pressure between said movable snd sta- REFERENCES CITED tionary contact means and concomitantly ma The following references are of record in the taining said position of said switch am, said me (this abutments being cooperable with said support to equalize said pressure between each contact or UNITED STATES PATENTS said pair, and condition responsive means car- D ried by said casing and being en'ective for over- T 3212 July 3 1917 coming said yieldable means to rotate said switch 166o256 Come lm arm and relieve said pressure while said yieid- 2272249 a; lm able means maintains said position of said switch 10 2'296374 Weber 1m m I I 1 s W R 2,389,880 Weber Nov. 2'7, 1945 WILLIAM S. KUNZLER. 

